package com.ywk.pattern._21_singleton._21_6_DCL;

//双检锁/双重校验锁
public class Singleton {
    private volatile static Singleton instance;

    private Singleton() {

    }

    public static Singleton getInstance() {
        if (instance == null) {
            synchronized (Singleton.class) {
                if (instance == null) {
                    instance = new Singleton();
                }

            }
        }
        return instance;
    }
}
